This invention relates to an automatic sewing machine and more particularly, to an automatic sewing machine of the type in which a seam consisting of a predetermined number of stitches is formed as a holding member holding a workpiece thereon moves horizontally to and away from a needle drop position and which ceases to operation at the completion of the seam formation.
As automatic sewing machines, cycle sewing machines such as tacking, button hole darning and embroidering sewing machines have been known. As one of such automatic sewing machines, of late, an electrically controlled sewing machine has been proposed. In the electrically controlled sewing machine, the workpiece holding member is operatively connected to a pair of pulse motors for driving the holding member in X and Y directions, respectively and a seam in a predetermined pattern is formed by moving the holding member in the X and Y directions under the control of the pulse motors. However, in the prior art electrically controlled sewing machine, connection means such as a timing belt and a chain connect between the pulse motors and workpiece holding member and as a result, the electrically controlled sewing machine is inevitably complicate in construction and troublesome in assembling. In addition, because of increase in the number of components due to the provision of the connection means between the pulse motors and workpiece holding member, the step positions of the pulse motors and the displaced positions of the workpiece holding member tend to deviate from their predetermined or proper relationship resulting in incorrect needle drop position. The incorrect needle drop position leads to formation of unshapely seams in tacking and embroidering sewing machines and needle drop at an area to be cut and subsequent thread cutting by a knife in button hole darning sewing machines whereby the obtained sewn products are of inferior quality.